Dental crown extension or lengthening is an osseous remodeling, used in restorative dentistry to recreate the biologic width and/or to correct the proportions of teeth and gums. Typically, the conventional method or procedure involves a scalloped incision to recreate the proposed gingival height, a gingival flap and approximately two millimeters (2 mm) of bone remodeling, measured from the new gingival margin to preserve the biological width. Bone removal can be carried out with a sharp manual instrument, with a conventional rotating drill or an electric piezosurgery unit.
However, this procedure is by nature, invasive and complex to execute, making the aesthetic results often unpredictable, since repositioning of the gingival flap requires the ability to maintain the planned proposed gingival margin when suturing it to the palate gum. Furthermore, measurements are difficult and inaccurate since the gingival margin is loose the reference points are mobile and there is a permanent risk of tooth damage by using the conventional instruments.
It can be appreciated that the techniques currently in use are effective, but they have not been embraced widely by the dental community, since they require extensive gingival flap elevation associated to postoperative discomfort and high risk of complications, as loss of interproximal papilla, regrowth, swelling, pain, bruising, root sensitivity, root resorption and irreversible root damage. The period of convalescence typically starts from one week, but definitive restoration of the teeth often can only be performed after approximately six months. All of these reasons lead to low acceptance for the patient.
The conventional method cannot be carried out without a gingival flap, because with a blind flapless technique, the required control of the bone depth remodeling does not exist. The instruments or piezoelectric tips used for these operations do not have the dimensions to introduce it under the attached gum without flap elevation nor the option to make the precise removal of 2-3 millimeters of bone tissue from the gingival margin. Moreover, rotating drills or piezoelectric tips act indistinctively on both bone and teeth, such that it is possible to damage the delicate structures of the teeth that the method is intended to enhance.
Accordingly, it would be desirable to have an ultrasonic tip, which can be used with a minimally invasive surgical method for crown lengthening, and which avoids teeth injuries, sutures, and postoperative convalescence periods.